How to Upgrade an Aquarium Filter (and Save Money!)

You may have noticed in the instructions that you need to replace the filter cartridge every month if you buy a hang-on-back filter at the pet shop. Most beginner fish keepers don’t realize that you can replace those disposable cartridges with reusable filter media that can last for the lifetime of the filter. In this article, we teach you how to optimize your aquarium filter in four simple steps, using only a pair of scissors.

Step 1: Get a Prefilter Sponge

Beneficial bacteria are a naturally occurring form of biological filtration that consume the toxic nitrogen compounds produced by your fish’s waste, thus making the water safer for the fish to live in. They will grow on any type of underwater surface, including gravel and walls. Prefilter sponges are a great way to encourage them growth. (If you aren’t familiar with the three types of filtration – mechanical, biological, and chemical – you can read our article called Fish Tank Filters: Which One Should You Get?)

Prefilter sponge is a cylindrical foam that fits over your intake tube for your hang-on or canister filter. It looks like a shoe on a foot. Not only do prefilter sponges grow lots of beneficial bacteria, but they also help with mechanical filtration by preventing food, small fish, leaves, and other large debris from getting sucked into the filter’s motor compartment.

Pick an appropriately sized prefilter sponge for your filter, and you can easily double its filtration capacity.

The prefilter sponge should be installed so that it covers the intake tube’s slits. This will ensure that the filter draws water out of the sponge to provide maximum filtration. However, if you find your prefilter sponge is a little too loose, you can cut off a sliver of sponge and stuff it down the center hole to make a snugger fit. Also, if you notice that the water flow from your filter is decreasing, make sure to regularly clean the prefilter sponge about once a month by squeezing out the debris in a bucket of old aquarium water.

Step 2: Dispose the Disposable Carridge

We mentioned at the beginning that the filter’s default cartridge should be replaced. It is so bad, you ask? The fact is that most cartridges are made out of fine filter padding for mechanical filtration (to remove debris from the water) with activated carbon inside for chemical filtration (to remove medications and other impurities from the water). Unfortunately, activated carbon and fine filter padding quickly get clogged up with impurities and waste, reducing their effectiveness. Also, their dense materials can be difficult to clean and reuse.

Step 3: Install Reusable Filter Media

The filter compartment, where the cartridge was supposed to be placed, should be filled with bio rings and coarse foam sponge. These media types can be reused, offer more biological filtration surface, and can even increase the filtration capacity by up to fourfold. You don’t have to replace the filter media or throw away any beneficial bacteria. Just rinse them in old aquarium water once per month.

Coarse spongy pads can remove any debris from water and can be used again by rinsing on a monthly basis.

For mechanical filtration, we like to use coarse sponge pads that you can cut to fit any compartment in a hang-on-back or canister filter. Because they are not easy to clog, can last for 10 years, and are relatively inexpensive, we offer coarse sponges. For biological filtration, you can use bags of bio rings that have lots of porous holes for beneficial bacteria to grow in. You can use a resealable bag to fit the bag into the filter.

Bio rings help boost the growth of biological bacteria, which consume the toxic nitrogen compounds produced by fish waste.

Find out the direction that the water flows through your filter media before you install it. AquaClear filters are an example. The water flows upwards from its bottom to the top, then falls back into the aquarium. Place the coarse sponge pad on the bottom of the compartment, so that the water hits it first. Then place the bio rings above the sponge. The coarse sponge will remove most gunk from the water, and the bio rings with smaller pores won’t become as filthy.

If you have a nano tank for your betta fish that comes with a built-in filter compartment, you may not be able to fit as many layers inside. Therefore, we recommend switching out the disposable cartridge with only coarse sponge, which provides both mechanical and beneficial filtration.

Step 4: Clean the Reusable Media Filter

You should maintain your filter by cleaning it once a month. Mechanical filtration (such as prefilter sponges and sponge pads) acts like a garbage can that collects waste – which means you as the fish owner are still responsible for cleaning the filter media (in other words, “emptying” the trash can before it overflows and causes water to spill out of the aquarium).

How do I upgrade my filter to get crystal clear water?

If you want to really polish the water, simply add a layer of fine poly pad that has very small pores and is capable of removing tiny particulate. Like the cartridges, these fine filter pads will eventually need to be thrown out and replaced once they become saturated with debris. The advantages of these filters are that they are inexpensive and can be cut to any size.

Poly pads are great at removing fine particles so that you get crystal-clear water and your fish look like they’re flying in midair.

Final Thoughts

Reusable filter media can make your aquarium system more efficient and help maintain high water quality. Although it may cost more upfront, reusable media can last for many years, which will save you lots of money over the long-term.